JP2001311800A - Electron beam irradiation target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam irradiation target, easy to replace if problems including local heat due to electron beam irradiation happen and capable of uniformly receiving the irradiation of an electron beam in a wide angle range and uniformly generating heat. SOLUTION: The target to be irradiated with a high-voltage and large-current scanned electron beam comprises a number of metal tubes in which a cooling liquid is distributed, arrayed along an irradiation plane of the electron beam. The metal tubes are arrayed in at least two layers, and the first-layer metal tubes are shifted from the second-layer metal tubes and the arrays of the metal tubes are divided in plural sections so that the electron beam applied through gaps between the arrays of the first-layer metal tubes can irradiate the metal tubes arrayed in the second layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiation apparatus used for treating exhaust gas discharged from a thermal power plant, for example, or a large current irradiation apparatus used for modifying a substance such as resin cross-linking. The present invention relates to an electron beam irradiation target suitable for use in a test of an electron beam irradiation apparatus or the like. Specifically, the present invention relates to an electron beam irradiation target that irradiates an electron beam when testing an electron beam irradiation apparatus that emits an electron beam into the atmosphere while scanning the electron beam from a window foil for taking out electrons.

[0002]

2. Description of the Related Art At present, global warming and acid rain caused by air pollution, which have become a problem worldwide, are present in combustion exhaust gas discharged from, for example, thermal power plants.
It is thought to be due to components such as Ox. These S
As a method for removing harmful components such as Ox and NOx, desulfurization and denitration (removal of harmful components such as SOx and NOx) are performed by irradiating combustion exhaust gas with an electron beam. In such an electron beam irradiation apparatus, it is necessary to emit a high-current electron beam accelerated in a vacuum at a high speed into the atmosphere while scanning as widely as possible. For this reason, a window foil made of a thin film of titanium or the like having a high transmission efficiency for high-speed electrons is generally used for extracting an electron beam. In the irradiation of the electron beam, for example, the electron beam is scanned in a range of 3 m × 0.6 m.

[0003]

In a test of such an electron beam irradiation apparatus, an electron beam of a high voltage and a large current is emitted into the atmosphere from a window frame while being scanned. It is necessary to arrange on the irradiation surface of the electron beam. This is because, if the electron beam is emitted in a state where the object to be irradiated with the electron beam does not exist, for example, the member that stores the object to be irradiated is irradiated with the electron beam, which has an undesirable effect. As such an electron beam irradiation target,
In general, a large number of metal tubes through which a coolant flows are arranged and used so that the electron beam can be completely shielded. Thereby, the heat generated by the electron beam irradiation is removed by the cooling liquid such as water flowing inside the metal tube, and the test of the electron beam irradiation apparatus can be performed while processing the heat generated by the electron beam irradiation.

[0004] However, as for the irradiation of the electron beam, for example, as described above, the irradiation surface of 3m x 0.6m is scanned in a substantially rectangular shape. There is a portion where the irradiation density of the scanned electron beam is high, and there is a problem that heat generation of the electron beam irradiation target in that portion increases. If the heat generation increases in a portion where the electron beam irradiation density is high as described above, there is a problem that the metal tube easily buckles because the thermal expansion of the metal tube increases in that portion. In addition, Ca ions in the cooling water reach the saturation limit, and Ca compounds (eg, CaC
O ₃ ) and precipitate. When the Ca compound precipitates, the heat transfer coefficient deteriorates abruptly at that part, the temperature further rises, the precipitation proceeds at an accelerated rate, and the metal tube breaks due to the temperature rise, causing problems such as coolant leakage. Will be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electron beam irradiation target that can be easily replaced even when a problem such as local heat generation due to electron beam irradiation occurs. And It is another object of the present invention to provide an electron beam irradiation target capable of uniformly receiving irradiation of an electron beam scanned at an angle over a wide range and generating heat uniformly.

[0006]

According to a first aspect of the present invention, there is provided a target for scanning and irradiating an electron beam having a high voltage and a large current, wherein a plurality of metal tubes through which a cooling liquid flows are connected to the electron tube. An electron beam irradiation target characterized by being arranged along a line irradiation surface and dividing the arrangement of the metal tubes into a plurality of sections.

In this way, in the test of the electron beam irradiation apparatus, the arrangement of the metal tubes is divided into a plurality of sections even when the electron beam irradiation is locally concentrated and the portion generates a large amount of heat. Only that part can be replaced. Therefore, the test of the electron beam irradiation device can be performed safely and reliably.

In the invention according to claim 2, the arrangement of the metal tubes is at least two layers, and the electron beams irradiated through the gaps between the arrangement of the first layers of metal tubes are arranged in the second layer. An electron beam irradiation target, wherein the metal tube of the first layer and the metal tube of the second layer are staggered so as to irradiate the metal tube.

Thus, since all of the electron beams irradiated from the electron beam irradiation device are irradiated on the metal tube, the problem that the electron beam passes through the irradiation target and irradiates the peripheral portion is eliminated. In addition, since the electron beam is applied to both the first layer side metal tube and the second layer side metal tube, heat generated between the two layers is dispersed. Therefore, metal tube wear and Ca in the metal tube
A target for electron beam irradiation that can reduce precipitation and can be used for a long time can be obtained.

According to a third aspect of the present invention, there is provided a target for scanning and irradiating an electron beam having a high voltage and a large current, wherein a number of metal tubes through which a cooling liquid flows are formed along the irradiation surface of the electron beam. The metal tubes are arranged in at least two layers, and the first tube is arranged such that the electron beam irradiated through the gap between the arrays of the metal tubes in the first layer irradiates the metal tubes arranged in the second layer. An electron beam irradiation target, wherein a metal tube of a layer and a metal tube of a second layer are arranged so as to be shifted from each other, and the arrangement of the metal tubes is divided into a plurality of sections.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1A shows an electron beam irradiation apparatus according to the present invention and an arrangement of irradiation targets used for the test. This electron beam irradiation apparatus is used for treating combustion exhaust gas, and includes a power supply device 10 for generating a DC high voltage, an electron beam irradiation apparatus 11 for irradiating an electron beam to the combustion exhaust gas,
It mainly comprises a flue gas flow path 19 provided along the window foil 15 which is an electron beam irradiation outlet. For example, the electron beam emitted to the outside from the window foil 15 made of a thin plate of Ti or the like is extremely oxidized by irradiating molecules such as oxygen (O ₂ ) and water vapor (H ₂ O) in the combustion exhaust gas. It becomes a strong radical such as OH, O, and HO ₂ . And these radicals form SOx and NOx
Oxidizes harmful components such as sulfuric acid and nitric acid as intermediate products. These intermediate products react with ammonia gas (NH ₃ ) charged in advance, become ammonium sulfate and ammonium nitrate, and are collected as raw materials for fertilizer. Therefore, in such an exhaust gas treatment system, it is possible to remove harmful components such as SOx and NOx from the combustion exhaust gas and to collect them as raw materials for fertilizers such as ammonium sulfate and ammonium nitrate which are useful as by-products. Can be.

Here, the electron beam irradiation device 11 is formed by a thermionic electron source 12 such as a thermionic filament, an accelerating tube 13 for accelerating the electrons emitted from the thermionic electron source 12, and the accelerating tube. A deflection coil (electromagnet) 16 for controlling the beam diameter by applying a magnetic field to the high-energy electron beam and applying a magnetic field by a square-wave current to deflect the electron beam in the lateral direction; It mainly includes a scanning coil (electromagnet) 17 that scans the electron beam in the longitudinal direction by applying a magnetic field to the electron beam whose beam diameter is controlled. Among them, the source of the electron beam, the electrode for acceleration, the magnetic pole for deflection scanning, and the like are provided in the envelope (vacuum container) 18a,
It housed within 18b, inside the envelope 10 - are maintained under high vacuum atmosphere of about ^{6 Pa.} The formed high-energy electron beam is deflected and scanned by supplying current from the power sources 21 and 22 to the deflection coil 16 and the scanning coil 17 to form a magnetic field by the electromagnet, thereby irradiating the irradiation window (window). The exhaust gas is emitted from the foil 15 into a predetermined range of the flow path 19 of the exhaust gas.

In such an electron beam irradiation apparatus, it is necessary to extract an electron beam accelerated at high speed in a vacuum to the atmosphere as described above. For this reason, a window foil 15 made of a pure titanium film or a titanium alloy film having a thickness of several tens of μm is generally used for extracting an electron beam in order to achieve high electron transmission efficiency.
Irradiation of the electron beam in such an electron beam irradiation apparatus is performed by deflecting in the transverse direction by the deflecting coil 16 and scanning as described above so that the electron beam is uniformly emitted from the window foil having a relatively large area. Scanning is performed in the longitudinal direction by the coil 17.
A triangular wave current is supplied to the scanning coil 17 by the triangular wave generating power supply 2.
2 to scan the electron beam in the longitudinal direction (Y direction) as shown in FIG. On the other hand, a trapezoidal current is supplied to the deflection coil 16 from the square wave generation power supply 21, whereby the electron beam is scanned in the short direction (X direction). The triangular wave current and the square wave current are synchronized. In this case, the triangular wave is synchronized so that the peak of the triangle wave coincides with the midpoint of the rising of the square wave. Accordingly, the trajectory of the electron beam scanned by the deflecting coil 16 and the scanning coil 17 has a long hexagonal shape as indicated by reference numeral 31 in FIG.

At the time of the test operation of the electron beam irradiation apparatus 11, there is no exhaust gas or the like to be irradiated with the electron beam in the flow path 19. For this reason, when the electron beam of high voltage and large current is emitted from the window foil 15 during the test operation of the electron beam irradiation device, the electron beam reaches the periphery of the flow path 19 as it is,
There is a problem in that this is heated to reform the periphery of the flow path itself. For this reason, during the test operation of the electron beam irradiation device, the target 30 is arranged, and the target 30 is irradiated with the electron beam to shield the peripheral portion of the flow path. FIG.
In (a), the electron beam irradiation target 30 is arranged at a position where the flow path 19 is closed, but this position can be changed as appropriate.

The electron beam irradiation target 30 is shown in FIG.
As shown in (b), it is divided into five blocks. The target of each block is composed of a large number of metal tubes through which cooling water flows, as described later. Numeral 31 in the figure indicates a scanning trajectory of the center of the electron beam. As shown, the center of the electron beam is scanned along a long hexagonal trajectory. In the scanning in the longitudinal direction, the portions A and A 'in the figure have the electron beam stagnation or have a partially high heat generation density. Therefore, in this portion where the electron beam irradiation density is high inside the metal tube due to the irradiation of the electron beam, Ca precipitates and becomes higher in temperature, so that the metal tube tends to be damaged. For this reason, the target 30 is divided into a plurality of blocks and can be replaced before an accident such as water leakage occurs, so that a block that is significantly worn can be replaced.

FIGS. 2A, 2B and 2C show a target 3
3A, 3B, and 3C show enlarged cross sections in the longitudinal direction at positions A, B, and C of the target, and FIG. 4 shows enlarged cross sections in the lateral direction of the target. I have. As shown in the figure, the target 30 has a large number of metal tubes 32 and 33 through which cooling water flows. The metal tubes 32 and 33 are arranged in two layers, an upper layer and a lower layer. Headers 3 on both sides of metal tubes 32 and 33
4 and 35 are arranged, and the water supply and drainage pipe 3
6, 37 are connected respectively. Therefore, water flows into the header 34 from one of the water supply / drain pipes 36, and cooling water flows from the header 34 to the other header 35 through a number of metal pipes 32, 33, and the cooling water further flows to the outside through the water supply / drain pipe 37. Is discharged. At the ends of the plumbing pipes 36 and 37, O
Ring type pipe seal members 38 and 39 are arranged,
It is connected to an external cooling water pipe. Therefore, when the block of the target 30 is replaced, the pipe seal member is loosened, and the water supply / drain pipes 36 and 37 can be easily removed and reattached.

FIGS. 3 (a), 3 (b), and 3 (c) are respectively shown in FIG.
2 shows the arrangement relationship of the metal tubes of the A, B, and C portions. 3 (a), 3 (b) and 3 (c), each arrow indicates the direction of irradiation of the electron beam. That is, as shown in FIG. 1, upon irradiation with an electron beam, the electron beam is deflected and scanned at a considerably large angle along its longitudinal direction. Therefore, the irradiation direction of the electron beam is oblique to the part A near the end of the target 30 in FIG. On the other hand, in the part B closer to the center, the electron beam enters from an oblique direction that is slightly vertical. Then, in the portion C closer to the center, the electron beam enters from a direction nearly perpendicular. Accordingly, by providing an appropriate shift between the arrangement of the upper metal tube 32 and the arrangement of the lower metal tube 33 in accordance with the irradiation direction of the electron beam, all the electron beams are shielded by the target. Can be arranged.

That is, in part A near the end, a two-layer metal tube 3
2, 33 are arranged in a substantially vertical direction. This makes it possible to shield all the electron beams incident from oblique directions without passing through the gap between the metal tubes. Similarly, in the portion B, the space between the upper metal tube 32 and the lower metal tube 33 is slightly shifted from the vertical direction. Thereby, all of the electron beams in the direction of the arrow shown in FIG. 3B can be shielded by the metal tubes 32 and 33. Further, in the portion C near the center of the target 30, the upper metal tube 3
2, the lower metal tube 33 is displaced in a staggered manner. This makes it possible to shield all of the electron beams incident in the direction of the arrow close to the vertical direction. In this way, by adjusting the positional relationship between the upper metal tube 32 and the lower metal tube 33 so that all of the electron beams can be shielded, the electron beam passes between the metal tubes and the peripheral portion thereof. To the upper metal tube and the lower metal tube can be efficiently irradiated with an electron beam, and the heat dissipation and heat absorption can be made nearly uniform. , The thermal expansion of the metal tubes 32 and 33 becomes equal, and buckling is less likely to occur.

Next, a method of using the electron beam irradiation target will be described. In the test of the electron beam irradiation apparatus, the target 30 is arranged at a portion from which electrons are emitted. This target is stored in block 30 as described above.
Since they are divided into a, 30b, 30c, 30d, and 30e, they are individually carried into a portion to be irradiated with an electron beam and arranged using a suitable frame or the like. Then, pipes for water supply and drainage are connected to the water supply and drainage pipes 36 and 37 from outside using pipe seal members 38 and 39, respectively. Then, an operation test of the electron beam irradiation apparatus is performed while cooling water is circulated from the outside. At this time, the upper and lower metal tubes 32 and 33 of each block are used.
Are shifted according to the incident angle of the electron beam as described above. Thereby, the electron beam scanned at a wide angle is completely shielded by the target 30 and does not leak through the target 30 to the peripheral portion. Then, both the upper and lower metal tubes 32 and 33 are uniformly irradiated with the electron beam, and the heat dissipation can be made uniform. In the test of the electron beam irradiation apparatus, during the scanning of the electron beam, the electron beam may stagnate at the ends A and A 'of the longitudinal scanning as described above, and the portion may be locally heated, There is a portion where the electron beam density becomes high. In such a case, the metal tubes 32 and 33 are worn at that portion,
In such a case, the block can be replaced before an accident such as water leakage occurs. For replacement, the pipe seal members 38 and 39 may be removed, replaced with a block of the same shape, and connected to the external water supply / drainage again. As a result, the test can be easily continued. After the test of the electron beam irradiation apparatus is completed, the target 30 can be easily removed by removing each block and the water supply / drainage pipe from outside.

In the above description, the target 3
0 to blocks 30a, 30b, 30c, 30d, 30e
However, it is needless to say that the number of divisions can be appropriately changed according to the situation of the use site or the like. or,
In the above-described embodiment, an example has been described in which the metal pipes are arranged in two layers, the upper layer and the lower layer. However, the metal pipes may be arranged in three or more layers. However, from the viewpoint of uniform heat dissipation of each layer, it is preferable to use two layers.
In addition, although the case where water is used as the cooling water has been described, it is a matter of course that another cooling medium may be used.

[0022]

As described above, according to the electron beam irradiation target of the present invention, since the target is divided into a plurality of blocks, it is easy to replace the target, thereby causing a problem such as water leakage. The test of the electron beam irradiation device can be stably performed without any problem. In addition, by giving a shift corresponding to the electron beam irradiation direction between the upper metal tube and the lower metal tube in the target, the upper and lower metal tubes can be uniformly irradiated with the electron beam, Thereby, the wear of the metal tube due to the concentration of the electron beam can be reduced.

[Brief description of the drawings]

FIG. 1A is a diagram illustrating an arrangement relationship between an electron beam irradiation device and a target, and FIG. 1B is a diagram illustrating an example of an electron beam scanning locus on an electron beam irradiation target.

FIGS. 2A and 2B are views showing the overall configuration of an electron beam irradiation target, wherein FIG. 2A is a plan view, FIG. 2B is a cross-sectional view along a longitudinal direction, and FIG. It is sectional drawing.

3A is a diagram showing an arrangement of a metal tube in a portion A of FIG. 2A, FIG. 3B is a diagram showing an arrangement of a metal tube in a portion B of FIG. 2A, (C) is C in FIG.
It is a figure showing arrangement of a metal tube in a part.

FIG. 4 is an enlarged cross-sectional view of a target along a lateral direction.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 electron beam irradiation device 15 window foil 16 deflection coil (electromagnet) 17 scanning coil (electromagnet) 19 flow path 21 square wave generation power supply 22 triangular wave generation power supply 30 electron beam irradiation target 31 electron beam scanning locus 32 upper layer (first layer) Layer) side metal pipe 33 Lower layer (second layer) side metal pipe 34, 35 Header 36, 37 Water supply / drainage pipe 38, 39 Piping seal member A, A 'Turning point of electron beam orbit

Claims (3)

[Claims] 1. A target for scanning and irradiating an electron beam having a high voltage and a large current, wherein a plurality of metal tubes through which a cooling liquid flows are arranged along an irradiation surface of the electron beam. An electron beam irradiation target characterized by dividing the array of a plurality of sections. 2. A target for scanning and irradiating an electron beam having a high voltage and a large current, wherein a plurality of metal tubes through which a cooling liquid flows are arranged along an irradiation surface of the electron beam. Are arranged in at least two layers, and the first layer of metal tubes is arranged such that the electron beam irradiated through the gap between the arrays of the first layer of metal tubes irradiates the metal tubes arranged in the second layer. A target for electron beam irradiation, wherein the target and the metal tube of the second layer are displaced from each other. 3. A target for scanning and irradiating an electron beam having a high voltage and a large current, wherein a plurality of metal tubes through which a cooling liquid flows are arranged along an irradiation surface of the electron beam. Are arranged in at least two layers, and the first layer of metal tubes is arranged such that the electron beam irradiated through the gap between the arrays of the first layer of metal tubes irradiates the metal tubes arranged in the second layer. And a metal tube of the second layer being displaced from each other, and the arrangement of the metal tubes is divided into a plurality of sections.